NSWP: Predicting Geomagnetically Induced Fields Driven by Solar Wind Pressure Discontinuities

地磁感应电流是空间天气的直接后果。它们主要是由强烈和快速变化的电离层电流造成的，这种电流可能对地球表面的技术系统造成危险。由行星际激波通过引起的突然脉冲（SI）事件已被证明会在地面上产生足够大和足够快的磁场变化，从而导致大的GIC。该项目的目的是开发SI电流系统电离层部分的经验和物理模型，并利用这些模型计算和最终预测地球表面的地磁感应场。这项研究将通过利用地面磁力计的测量值结合电离层等离子体漂移的雷达测量值建立一个SI电流的经验模型来完成。此外，还将利用全球磁层模型和上游太阳风测量数据，建立一个基于物理学的太阳系电流系统模型，以评估其代表电流系统的能力。 这些模型电流系统的感应磁场和电场将使用被称为辅助源法的数值技术、复镜像法、以及通过利用大地电磁方程和地球电导率模型来计算。该项目的结果将是一个基于上游太阳风条件的预测模型，该模型将预测SI事件产生的地磁感应场的大小、位置和持续时间。此外，还将开发将联合收割机和雷达数据相结合的技术。这项研究具有重要的科学意义，因为已知大型GIC会对电网造成严重影响，有时会导致社会经济损失超过数千万美元。这项研究将涉及工程和物理系的本科生和研究生。

Geomagnetically induced currents (GICs) are a direct consequence of space weather. They are caused primarily by intense and rapidly varying ionospheric currents that can be hazardous to technological systems on the surface of the Earth. Sudden impulse (SI) events caused by the passage of interplanetary shocks have been shown to produce magnetic variations on the ground large and fast enough to cause large GICs. The aim of this project is to develop empirical and physics-based models of the ionospheric portion of the SI current system and use these models to calculate, and ultimately predict, the geomagnetically induced fields at the surface of the Earth. The study will be accomplished by developing an empirical model of the SI currents using measurements from ground-based magnetometers combined with radar measurements of the ionospheric plasma drift. Also, a physics-based model of the SI currents system will be developed using a global magnetospheric model and upstream solar wind measurements to evaluate its ability to represent the current system. The induced magnetic and electric fields from these model current system will be calculated using the numerical techniques known as the method of auxiliary sources, the complex image method, and by utilizing the magnetotelluric equations and a model of the Earth's conductivity. The result of the project will be a predictive model, based on the upstream solar wind conditions, that will forecast the size, location, and duration of geomagnetically induced fields produced by SI events. In addition, techniques that combine magnetometer and radar data will be developed. This research has important scientific relevance becaue large GICs are known to cause severe effects on electric power grids, sometimes resulting in socioeconomic losses that can exceed tens of millions of dollars. The research will involve both undergraduate and graduate students in the engineering and physics departments.